Pleating process for fabrics of thermoplastic fibers



Feb. 9, 1960 R. P. NIRENBERG 2,924,361

PLEATING PROCESS FOR FABRICS 0F THERMOPLASTIC FIBERS Filed Aug. 1:5, 1958 2 Sheets-Sheet 1 FIG-l INVENTOR ROBERT P N/RENBERG ATTORNE Ys Feb. 9, 1960 R. P. NIRENBERG PLEATING PROCESS FOR FABRICS OF THERMOPLASTIC FIBERS Filed Aug. 13, 1958 2 Sheets-Shee t 2 v INVENTOR. ROBERTA. N/RENBERG BY KW ATTORNEYS United StatesPatefit O PLEATING PROCESS FOR FABRICS OF THERMOPLASTIC FIBERS Robert P. Nirenberg, New York, N.Y., assignor to The Chemstrand Corporation, Decatur, Ala., a corporation of Delaware Application August 13, 1958, Serial No. 754,772

12 Claims. (Cl. 223-33) This invention relates to a process for pleating fabrics of thermoplastic fibers and more particularly to a process for producing improved pleated fabrics of such thermoplastic fibers.

Thermoplastic fibers, including acrylonitrile polymer fibers, particularly those containing at least 70 percent by weight of acrylonitrile, nylon, Dacron, Vinyon N, and vinyl and vinylidine halide fibers such as Vinyon, saran, etc., are being widely employed in the design and construction of textile fabrics, constituting in some cases the entire fiber content, and in other cases blended with other thermoplastic fibers and/or with one or more of the natural and non-thermoplastic fibers. Wide scale use of these fabrics is being made in clothing design and other uses where pleating in various forms is desirable. However, the appearance of the pleated fabrics has frequently not been of acceptable quality because of certain properties of the thermoplastic fibers and the nature of the pleating and pleat-setting operation as conventionally conducted.

Conventionally, pleating of textile fabrics has been conducted on a piece basis, particularly when such fabrics are to be employed in production of various types of clothing. It is the common practice to place a piece of fabric to be pleated between two sheets of paper or similar material which have been previously folded into the desired form which it is desired to produce in thepleated fabric. The folded pattern sheets or templates, known as pleating patterns or pleat formers, are flattened and the fabric to be pleated placed between them in a flattened condition. After the fabric has been placed between the pattern sheets the pattern sheets and fabric are folded or rolled together in such a manner that the fabric will be folded into the same form as the pattern sheets. The pattern sheets and fabric are then placed upon an unfolded sheet of paper or other suitable material and the entire assembly is rolled into cylindrical form or wrapped as a recthe standard or conventional operations outlined above.

These imperfections in the fabric have rendered them unacceptable or at least of second quality. In the case of some types of pleats, such as theso-called knife pleats, the degree of sharpness desired has not been retained after the fabrics have been removed from the pleating pattern and further handled in the manufacture of clothing. Likewise, there has frequently resulted in the case of fabrics containing thermoplastic fibers, the development of shine or glaze on the surface of the pleated fabric. or cloth. All these imperfections have created 'setiousdisadvantages to the use of pleating 'in clothing "ice and textile design. The production of inferior, unmerchantable pleated fabrics is extremely costly to the pleater. The occurrence of imperfections, particularly in fabrics containing thermoplastic fibers, has seriously limited the fashion and design scope of apparel manufacturers in the use of such fabrics. The difiiculty of securing satisfactory pleating has likewise reduced the versatility of a large group of fabrics woven by fabric mills. Consequently, there has long been desired a successful method of pleating fabrics containing thermoplastic fibers which. would produce a much lower incidence of the imperfections referred to above and, conversely, a muchhigher level of commercially acceptable production.

The reasons for the occurrence of the imperfections such as cockle, pucker, ripple, and bubble are many, but may largely be attributed to five principal factors. Deviations in the surface pleating pattern such as warping or bubbling in the paper of the pattern forms pockets in the pattern in which fabrics may fall and be molded in pleating operations, and conversely such areas in the pleating pattern which have bubbled may impress themselves upon the fabric in a manner akin to embossing. Inherent instability of the fabric construction which produces shrinkages or extensions in the cloth when exposed to conventional pleating practices including the heating required in pleat-setting are responsible for certain of the above conditions. In hand pleating the fabric lying between the bottom and top layers of the pleating patterns or formers is exposed to variations of tension due to the nature of the pleating pattern itself, in addition to inability to maintain uniform tension when folding or rolling the pleat formers or patterns. Conventional pleating practice requires the setting or baking of the pleated fabrics by placing the rolled or folded pattern containing the sandwiched fabric in a steam box or autoclave for the time necessary to set the pleats. Since the moisture of the steam and the heat do not penetrate the pleating patterns uniformly, temperature differentials are established within the pleating pattern in proportion to the variation of insulating factors such as air space, density differences in the rolled or folded pattern, the amount and type of paper or fabric used to wrap around the patterns and fabrics, etc. These factors cause the pleats to vary in sharpness and in appearance within any given assembly of fabric and pleating patterns. Because of the above non-uniformity of penetration of heat and moisture when patterns contain various reversals of the pleating planes or pleated planes of non-parallel sides or variation of the pleated planes contained in a repeat of the pleat pattern the fabric or cloth lying therein will have areas of surface which are slack or loose. More air space is found in these slack areas permitting the fabric and pattern to shift. These air spaces also allow a greater degree of moisture condensation upon the fabric thereby permitting a greater stress-strain differential in slack and taut areas of the pattern. For all the above reasons, and possibly others, pleating in thepiece of fabrics C0111 taining thermoplastic fibers has presented many problems, solutions to which have long been sought.

The principal object of the instant invention is to eliminate or reduce the development of cockle, pucker, ripple, or bubble during and after the pleating of fabrics containing thermoplastic fibers. A further object is to enhance the sharpness of the pleats obtained in such pleating operations. A still further object is to reduce or eliminate the development of shine or glaze in pleated fabrics or cloths containing thermoplastic fibers. Still further objects will appear from the discussion of the instant invention hereinafter.

The above and other objects of the invention can be accomplished by a process for pleating fabrics containing thermoplastic fibers or filaments which comprises placing and securing one or more layers of fabric to be pleated, dampened with water, in an assembly of pleating patterns arranged in registered, or pleating, relationship and extended to from 80 to 90 percent of the maximum extensible length thereof. The assembly of pleating patterns isextended to maximum extensible length and secured, thereby simultaneously applying tension to the layers of fabric secured thereto. The layered assembly of pleatpatterns and fabric is then adjusted to pleat-setting position by folding or rolling so as to form pleats in the said fabric, and the said assembly wrapped and bound. Thereafter, the wrapped and bound assembly is heated at a temperature of at least 200 F. for a time suflicient to dry the fabric in the assembly, and then slowly cooled at a rate not to exceed 6 F. per minute until the temperature in the interior of the assembly is not greater than 90 F. Finally, the thus pleated fabric is separated from the assembly. It has unexpectedly been found that the above pleating process results in the elimination or substantial reduction of cookie, pucker, ripple or bubble in the thus pleated fabrics containing thermoplastic fibers. In addition, sharpness of the resulting pleats is enhanced. Furthermore, the occurrence of shine or glaze in the thus pleated fabric is eliminated or substantially reduced.

The process of the instant invention is more specifically described with reference to the attached drawing wherein: Figure 1 is a plan view of one form of apparatus suitable for use in the instant process.

. Figure 2 is a side elevation view of the apparatus shown in Figure 1.

- Figure 3 is a side elevation view of the apparatus shown in Figure 1 in fully assembled, extended position.

Figure 4 is an enlarged view of the apparatus of Figure -1 illustrating the formation of pleats by adjusting the assembly of pleating patterns and fabric.

Figure 5 is a view of the wrapped and bound assembly preparatory to setting the pleats in the fabric.

With reference to Figures 1 and 2, preparatory to pleating a fabric a set of pleating patterns or pleat formers consisting of two parts, an upper pleating pattern 2 and a lower pleating pattern 3, are secured at one end 4 by suitable clamping means 5 to a plane surface 6, such as a table, bench, or the like. The upper pattern 2 is shown rolled or folded back from the lower pattern 3 toward the secured end 4 to expose a suificient area of the lower pattern 3 to accommodate the fabric to be pleated. The lower pattern 3 is shown extended to from 80 to 90'percent, and preferably approximately 90 percent, of its maximum extensible length and secured in that position to the plane surface 6 by clamping means 8 Pleating patterns may be secured by any commonly employed clamps or other suitable mechanical means. Any type of pleating patterns or formers commonly used in commercial pleating operations, such as heavy paper, paperboard, or like sheet materials, may be employed in the process of this invention.

There is then placed upon the partially extended lower pleating pattern 3 one or more layers of fabric or cloth to be pleated and the said fabric properly aligned for the desired pleat design. The fabric it) in its extended position is then secured under slight tension to the lower pleating pattern 3 at a number of points around the perimeter of the fabric by means of staples 9 or other suitable mechanical means such as pins, hooks, etc. Alternatively, the fabric 10 may also be secured to the lower pleating pattern 3 by means of any liquid or solid adhesive which can be suitably removed from the fabric at the completion of the pleating process, the use of staples 9 as shown in the drawing being by way of illustration only. The fabric 10 is secured to the lower pleating pattern 3 in such a manner that it is securely held to the partially extended lower pleating pattern with slight tension, but without producing visible stresses, strains, or distortions in the plane of the said fabric or cloth.

The fabric or cloth It) may be dampened but not oversaturated with water prior to its positioning on the lower pleating pattern 3. The preferred method, however, is to secure the dry fabric to the lower pleating pattern, as shown in Figures 1 and 2, and then to dampen the secured fabric with water by spraying, sponging, brushing, etc. Water alone, of the quality commonly available in textile processing plants or mills has been found to be suitable in the instant process. However, the even penetration of the water into the interstices of the fabric is aided by the inclusion in the water applied to the fabric of between 0.5 and 1.5 percent by volume of a detergent or wetting agent. Suitable detergents or wetting agents can be selected from among the classes of cationic, anionic, and non-ionic surface active agents.

With reference to Figure 3, the lower pleating pattern 3 having the layer or layers of fabric 10 to be pleated dampened with water and secured thereto by staples 9 is then extended to its maximum extensible length and again secured to the plane surface 6 by clamps 8. The upper pleating pattern 2 is positioned over the extended assembly of the lower pleating pattern 3 and the fabric It), secured to the plane surface 6 by clamps 8, and the pleatforming folds H of the said upper pleating pattern are matched and aligned with the corresponding folds 12 of the lower pleating pattern. Thereafter the upper pleating pattern 2 is secured to the lower pleating pattern 3 by means of staples 13 and 14, or other means, such as pins, hooks, etc. The extension of the lower pleating patterns 3 to which the fabric 10 is secured results in a simultaneous application of tension to the fabric. This additional tensioning of the fabric acts to minimize any inherent shrinkage or extension resulting from a particular construction of the fabric employed. It also acts to minimize any slackness or looseness in the fabric prior to forming the pleats therein.

The desired pleat design is then formed in the fabric assembled between the upper and lower pleating patterns. This forming of the pleats is accomplished by folding or rolling the patterns in their previously formed creases to the position in which the pleats are set. In the case of deep knife or accordion pleats, including sunburst or accordion pleats radiating from one selvedge of the fabric, the patterns are folded. In some knife pleat designs and box pleats the pleats are formed by tightly rolling the pleating patterns with the fabric assembled therebetween. It is generally desirable that maximum uniform pressure be applied to the assembly during this operation. The resulting folded or rolled assembly is then wrapped and bound in suitable fabric, paper, or like sheet materials and secured by means of tieing, strapping, or the like.

In Figure 4 there is illustrated the formation of accordion pleats in the fabric 10 by releasing clamps 8 holding one end of the assembly of pleating patterns 2 and 3 and fabric 10 and folding the assembly into the aligned folds of the patterns. Preferably the opposite end 4 of the pleating patterns 2 and 3 are left secured by clamps 5 until the folding operation is completed in order that maximum uniform pressure may be applied to the assembly of pleating patterns and fabric during folding. In this manner a length of fabric, paper, or like sheet material, not shown in Figure 4, can be positioned on the surface 6 of the table, bench, or the like for wrapping the folded assembly. The folded assembly of pleating patterns 2 and 3 and fabric 10 is then released from clamps 5 and wrapped in the fabric, paper, or like material and bound therein by means of tieing, strapping, or the like. Figure 5 illustrates the wrapped and bound assembly 20, wherein fabric 21 has been wrapped about the folded assembly of pleating patterns and fabric, bound by cords 22, and the ends of the fabric tied at 23 and 24. The wrapped and bound assembly 20 is now ready to be heated in order to dry the fabric and set the pleats therein.

The wrapped and bound assembly of pleating patterns and fabric, as illustrated by Figure 5, is then transferred to a chamber suitable for heating the assembly through outwith either steam or dry heat to a temperature of at least 200 F. and for a time sufiicient to dry the fabric in theassembly. The heating chamber may take the form of a steam box, or, preferably, an autoclave. Any enclosure capable of maintaining a temperature of from 200? to 212 F. at atmospheric pressure is suitable for useas a steam box. The time required for substantially drying a fabric in the pattern and fabric assembly ranges from about 15 to about 45 minutes in the steam box, depending upon theweight of the fabric being pleated. The heating and drying step is preferably carried out in an autoclave capable of producing temperatures in the range of about 225 F. to 260 F. The preferred range of temperatures for use in drying and setting the fabric being pleated is from 230 to 250 F. and for periods of time ranging from about 10 to minutes depending upon the temperature of the autoclave and the thickness of the fabric being pleated. For example, a fabric weighing up to approximately 4 ounces per square yard is suitably pleated by treatment in an autoclave at 235 F. for 10 minutes, while a fabric weighing between about 4 and about 8 ounces per square yard can be successfully pleated in an autoclave with a temperature of 250 F. for 10 minutes. On the other hand, a fabric weighing more than 8 ounces per square yard is pleated in an autoclave with a temperature of 250 F. for 15 minutes; In the case of very heavy fabrics the time in the autoclave can be extended sufliciently to insure drying and setting of the fabric. In general, greater times than those indicated are to be avoided in order not to produce shine or glaze on the pleated fabric because of prolonged heating after the fabric has become substantially dry. When heating times are employed as set out above, any tendency of the pleated fabric to display shine or glaze has been found to be substantially prevented.

When the pleat-setting operation involving heating and drying the fabric has been completed the assembly of pleating patterns and fabric is removed from the heating chamber, autoclave, or steam box, and is cooled slowly under controlled conditions of heat in order to prevent sudden temperature drops within the assembly and consequent condensation of moisture therein which will tend to cause cockle, pucker, ripple, bubble, etc., in the pleated fabric. The assembly is cooled at a rate not to exceed a temperature loss of about 6 F. per minute, and preferably at about 4 F. per minute. This slow and controlled cooling is continued until the temperature in the core or interior of the assembly is not greater than 90 F., and preferably isabout 80 F. The

slow rate of cooling of the heat-set pleated fabric while still in the assembly of the pleating patterns and fabric is a very important feature of the instant process in that imperfections which may develop in the fabric as a result of uneven cooling are prevented. After the assembly of pleating patterns and fabric has cooled to the indicated interior temperature the assembly may be disassembled in Well-known manner and the pleated fabric produced suitably packaged for storage, shipment, or use, as desired.

As indicated above, the instant process for pleating fabrics is suitable for all thermoplastic fibers and filaments. It has been found particularly useful in the case of fabrics of acrylonitrile polymer fibers and filaments,

i.e. those prepared from polymers containing at least 70 percent by weight of acrylonitrile in polymerized form, or blends of natural or artificial fibers with such acrylonitrile polymer fibers or filaments. Thus, fabrics containing acrylonitrile polymer fibers alone and those faband filaments and blends thereof with natural and other non-thermoplastic fibers are amenable to this process. Fabrics containing such fibers or filaments as nylon, both hexamethylene adipamide and polycaprolactam, polyesters, such as polyethylene terephthalate, Vinyon-N and other blends of vinyl chloride and acrylonitrile polymers, the vinyl and vinylidine halidefibers, such as Vinyon, saran and others, polyolefins, such as polyethylene, and the thermoplastic cellulose derivative fibers, such as cellulose acetate, secondary cellulose acetate, and cellulose tri-acetat'e, can be pleated by the process of the invention. Generally, it may be said that any fabric containing at least about 5 percent by weight, and preferably at least 15 percent by weight, of thermoplastic fibers or filaments are suitable for employment of the above process.

The advantages of the process of the instant invention over those of the prior pleating art are several. The process of the instant invention eliminates, prevents or minimizes the effect of cockle, ripple, pucker, bubble, etc., appearing in the pleated fabric during the pleating operation. The uniform application of moisture on the fabric surface enables the heat generated during the pleatsetting operation to be conducted evenly throughout the fabric. It also reduces the possibility of sudden or high temperature differentials existing between the dry fabric, as in normal pleating operations, and the pleat-setting environment. The wetting-out or dampening also prevents the sudden application of wet heat to a dry fabric, as in some normal pleating procedures, which is floating or lies loosely in the pleating pattern causing uneven, unbalanced drying of cloth during pleat-setting with consequent distortion. Wetting-out or dampening of the fabric prevents the fabric from slipping, sliding or shifting Whileit is in the assembly with the pleating patterns in the pleating operation. Inherent fabric instability due to the design or construction thereof is minimized by the securing of the fabric to the pleating pattern with slight tension and its further tensioning upon the extension of the pattern to its maximum extensible length. Sharpness of the pleats formed is enhanced because of the tensioning and dampening of the fabric before forming the pleats. The presence of moisture due to the dampening or wetting-out procedure substantially reduces the tendency of the pleated fabric to shine or glaze because of prolonged heating of dry fabric as in normal pleating processes. The percentages of seconds or unacceptable quality, as compared with normal pleating operations, is considerably reduced by the use of the present process. From the above it will be apparent that the present invention provides a new and improved method of pleating fabrics containing thermoplastic fibers which is of greater efiiciency than the normal pleating methods and provides a process by which many commonly occurring fabric imperfections are eliminated or substantially reduced.

As many apparently widely different embodiments of this invention may be made by those skilled in the art without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.

I claim:

1. A process for pleating fabrics containing thermoplastic fibers or filaments which comprises placing and securing a Water dampened fabric in a pleating assembly comprising pleating patterns arranged in pleating relationship to each other and extended to to percent of the maximum extensible length thereof, extending said pleating assembly to the maximum extensible length thereof whereby said fabric is placed under tension, assembling said pleating assembly into pleat-setting position, wrapping and binding said assembly, heating the wrapped and bound assembly at a temperature of at least 200 F. for a time sufilcient to dry the fabric, slo'wly cooling the Wit-$351.

7 ass mb t r n t to ce d. 6 Pa m nu e n l the temperature in the interior of the assembly is not greater than 90 F., and thereafter separating the pleated fabric from the. assembly. i

2. The process as defined in claim 1 wherein the fabric is dampened with water containing in solution from 0.5 to 1.5 percent by volume of a wetting agent.

3.. A process for pleating fabrics containing thermoplastic fibers or filaments which comprises placing and securing a fabric in a pleating assembly comprising pleating patterns arranged in pleating relationship to each other and extended to 80 to 90 percent of the maximum extensible length thereof, dampening the fabric with water, extending said pleating assembly to the maximum extensible length thereof whereby said fabric is placed under tension, assembling said pleating assembly into pleat-setting position, wrapping and binding said assembly, heating the wrapped and bound assembly at a temperature of at least 200 F, for a time suflicient to dry the fabric, slowly coolingthe assembly at a rate not to exceed 6 F. per minute until the temperature in the interior of the assembly is not greater than 90 F., and thereafter separating the pleated fabric from the assembly.

4. The process as defined in claim 3 wherein the fabric is dampened with water containing in solution from 0.5 to 1.5 percent by volume of a wetting agent.

5. A process for pleating fabrics containing thermoplastic fibers or filaments which comprises placingand securing a water dampened fabric in a pleating assembly comprising pleating patterns arranged in pleating relationship to each other and extended to 80 to 90 percent of the maximum extensible length thereof, extending said pleating assembly to the maximum extensible length thereof whereby said fabric is placed under tension, folding said pleating assembly into pleat-setting position, wrapping and binding said assembly, heating the wrapped and bound assembly at a temperature of at least 200 F. for a time sufficient to dry the fabric, slowly cooling the assembly at a rate not to exceed 6 F. per minute until the temperature in the interior of the assembly is not greater than 90 F., and thereafter separating the pleated fabric from the assembly.

6. A process for pleating fabrics containing thermoplastic fibers or filaments which comprises placing and securing a water dampened fabric in a pleating assembly comprising pleating patterns arranged in pleating relationship to each other and extended to 80 to 90 percent .of the maximum extensible length thereof, extending said pleating assembly to the maximum extensible length thereof whereby said fabric is placed under tension, rolling said pleating assembly into pleat-setting position, wrapping and binding said assembly, heating the wrapped an beans a mb a sfiw rature s s last 290* for a time sunicient to dry the fabric, slowly cooling the assembly at a rate not to exceed .6- F. per minute until the temperature in the interior of the assembly isno t greater than 90 F and thereafter separating th e pleated fabric from the assembly. 7. The process as defined in claim 1 wherein the fabric to be pleated consists of two or more layers of fabric.

8. The process as defined in claim 1 wherein the wrapped and bound assembly is heated in an autoclave at a temperature of from 230 F. to 250 F. for a time sufficient to dry .the fabric. 1

9. The process as defined in claim 1 wherein the wrapped and bound assembly is heated in a steam at temperature of from 200 F. to 212 F. for a time stiflicient to dry the fabric. 7 i '7 10. The process as defined in claim 1 wherein the fabric contains at least 5 percentby weight of fibers pre: pared from polymers containing at least percent by weight of acrylonitrile in polymerized form.

11. The process as defined in claim 1 wherein the fabric contains at least 5 percent by weight of filaments prepared from polymers containing at least 70 percent by weight of filaments prepared from polymers containing at least 70 percent by weight of acrylonitrile inv polymerized form. v 12. A process for pleating fabrics containing thermoplastic fibers and filaments which comprises securing a lower pleating pattern at from to percent of the maximum extensible length thereof, securing thereto fabric, dampening the fabric with water, extending the lower pleating pattern to the maximum extensiblelength thereof whereby said fabric is placed under tension, securing thereto an upper pleating pattern in pleating relationship to the lower pleating pattern, assembling the resulting assembly of pleating patterns and fabric into pleat-setting position, wrapping and binding said assembly, heating the wrapped and bound assembly at a temperature of at least 200 F. for a time suflicient to dry the fabric, slowly cooling the assembly at a rate not to exceed 6 F. per minute until the temperature in the interio'r of the assembly is not greater than 90 F., and thereafter separating the pleated fabric from the assembly.

References Cited in the file of this patent UNITED STATES PATENTS Brown Dec. 24, 1957 UNITED STATES PATENT OFFICE I CERTIFICATE OF CORRECTION ppears in the printed specification requiring correction and that the said Letters low.

Column 8 1i nes 24 and 25 prepared from pol strike out ymers contain ing at least 7 Signed and sealed this 9th day of Angus of filaments 0 percent by weightfl t 196(La (SEAL) Attest: KARL He AXLINE ROBERT C. WATSON Attesting Oflicer Commissioner of Patents 

